Plasma processing apparatus
AssigneeTokyo Electron Limited
InventorsNorikazu Yamada, Toshifumi Tachikawa, Koichi Nagami
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Abstract
At a time point T0 when starting a process, a duty ratio of a high frequency power RF1 to which power modulation is performed is set to be an initial value (about 90%) which allows plasma to be ignited securely under any power modulating conditions. At the substantially same time of starting the process, the duty ratio of the high frequency power RF1 is gradually reduced from the initial value (about 90%) in a regular negative gradient or in a ramp waveform. At a time point t2 after a lapse of a preset time Td, the duty ratio has an originally set value Ds for an etching process. After the time point t2, the duty ratio is fixed or maintained at the set value Ds until the end (time point T4) of the process.
Claims7
A plasma processing apparatus, comprising:
- an evacuable processing vessel;
- a first electrode configured to support a substrate to be processed within the processing vessel;
- a second electrode provided to face the first electrode within the processing vessel;
- a processing gas supply unit configured to supply a processing gas into the processing vessel;
- a first power feed unit configured to apply a first power to either one of the first electrode and the second electrode to generate plasma of the processing gas within the processing vessel;
- a modulation controller configured to control the first power feed unit to perform a power modulation on the first power in a plasma process such that a first period during which the first power for plasma generation is turned on or set to be a first level and a second period during which the first power is turned off or set to be a second level lower than the first level are alternately repeated at a regular pulse frequency;
- and
- a duty ratio controller configured to set a duty ratio in the power modulation of the first power to be an initial value for plasma ignition, and then, reduce the duty ratio from the initial value to a preset value for the plasma process gradually or in a step shape during a preset transition time,
- wherein the reduction of the duty ratio in the power modulation of the first power is started at the substantially same time of starting application of the first power to either one of the first electrode and the second electrode, and
- wherein the first power has a frequency of about 13.56 MHz or higher.
Dependencies are inferred from the claim text.